2014 AA – New Year’s Earth impactor

2014 has started off with fireworks! The first designated asteroid of the year, discovered only half an hour before midnight on New Year’s Eve (Tucson local time) but 6.5 hours into 2014 in Universal (or Greenwich Mean) time by Richard Kowalski of the Mount Lemmon Survey, was an Earth impactor.

Based on 7 astrometric measurements taken over the course of 70 minutes, the Minor Planet Center’s orbit has determined that 2014 AA impacted the Earth around Jan. 2.2 +/- 0.4 UT somewhere along an arc stretching from the eastern Pacific Ocean, southern Nicaragua, Costa Rica, very northern Columbia and Venezuela, a long stretch of the Atlantic Ocean and the African countries of Senegal, Gambia, Mali, Burkina Faso, Niger, Chad and Sudan. Maps of the possible impact points have been produced by Bill Gray and can be found here and here. The most likely impact point is in the Atlantic Ocean off the coast of western Africa.

With an absolute magnitude of ~30.9, 2014 AA was likely a very small asteroid with a diameter on the order of 1-5  meters. Such an object would have posed no danger to the ground though small meteorites may have survived passage through the atmosphere. If it fell in the ocean there is a good chance that no one directly witnessed it though the signature of its resulting fireball may be found in weather satellite images.

This marks the second time that an asteroid was detected in space prior to impact. The first impactor, 2008 TC3, was also found by Rich Kowalski and the Mount Lemmon 1.5-m reflector. That body was observed to fall over northern Sudan and led to the recovery of many meteorites (named Almahata Sitta). More on the fall of 2008 TC3 and Almahata Sitta can be found at this blog (here, here, here, and here), the Meteoritical Bulletin and Wikipedia.

Note, that for every small asteroid discovered before hitting the Earth (of which we’ve seen only two) there are many thousands of similar sized objects (and countless smaller ones) that go undetected until seen as brilliant fireballs or meteors. Hopefully planned upgrades to current asteroid surveys such as the Catalina Sky Survey/Mount Lemmon Survey and future surveys like ATLAS will result in more warning time for incoming asteroids.

Awesome Fireball Event in central Russia

2012 DA14 may not be on a collision course with Earth later today but a smaller asteroid was. A major fireball (and most likely also a meteorite dropping event) occurred over the city of Chelyabinsk, Russia. Chelyabinsk is a city of 1+ million people located just to the East of the Ural Mountains and just north of the Russia-Kazakhstan border.

The fireball that occurred there this morning appeared brighter than the Sun and produced a sonic boom that shattered windows causing flying glass-induced injuries to hundreds of people. A large building in town also seems to have been damaged. Though it is still uncertain if this was due to a large meteorite or the sonic boom.

An event like this happening only hours before the close flyby of the ~45-meter in diameter asteroid 2012 DA14, begs the question of whether the two are linked. It is probably unlikely that the Chelyabinsk fireball and 2012 DA14 are related. Luckily there are so many great videos of the fireball that an accurate orbit for the asteroid that caused the fireball should be easily determined.

[Update: 2012 DA14 and the Russian fireball can not be related. The radiant (the region of the sky that a DA14 or a piece of DA14 would appear to come from) of DA14 is at the very far southern declination of -81 degrees. This is the reason why DA14 is only visible from the southern hemisphere as it approaches Earth. A radiant that far south could not produce a fireball over Russia which is in the northern hemisphere. Any pieces of DA14 would only be able to impact Earth over the southern hemisphere or a few degrees north of the Equator. The fact that the Russian fireball and the 2012 DA14 close approach are happening on the same day is just a coincidence.]

Up-to-date information can be found at RT, here and here, and RMNB.

Many videos have been posted. The first 2 show the fireball itself. The last 2 are videos of the resulting contrail. What is very impressive about the last two is that the videos also caught the sonic boom. In one of the videos you can hear glass shattering in the background. Simply awesome…

Recent Discoveries – Sept 17-24, 2010

Catching up on the last week in comet and asteroid discoveries… A week ago new NEA announcements were coming left and right but the flood completely stopped a few days before Full Moon. Most surveys take a break for a few days around Full Moon since the bright sky is really not conducive for finding much of anything.

Last week saw one and probably two comet discoveries. C/2010 S1 (LINEAR) is a large perihelion (q = 4.4 AU) long-period comet. Currently 17th magnitude and 8.5 AU from the Sun (almost the distance of Saturn), it should brighten to magnitude 12-13 near perihelion in the summer of 2013. This comet marks the 44th (non-SOHO-STEREO) comet discovery of the year and LINEAR’s 199th comet find.

2010 BK118 was first seen back in January by the WISE (Wide Infrared Space Explorer) spacecraft. WISE is conducting a survey of the sky at 4 infrared wavelengths. Though not specifically designed to find asteroids/comets, the spacecraft observes at wavelengths optimal for finding these types of objects. Though not identified as anything special back in January, it was independently rediscovered by LINEAR last week. After a few days of observation, January’s WISE object and this month’s LINEAR object were linked as one and the same. So far there have been no reports of cometary activity even though the orbit is very cometary (long-period type). If it is truly a extinct or dormant comet than it is very large for a comet nucleus at H = 10.2 and a diameter of ~60 km. I’d be very surprised if this object doesn’t turn out to be an actual comet when larger telescopes are pointed its way.

2010 SW3 passed within 0.0058 AU of Earth on Sept. 10. This distance equals 540,000 miles, 860,000 km or 2.1 Lunar Distances. The 10 to 30 meter in diameter rock was discovered by the Mount Lemmon Survey eight days after close approach.

Asteroid    Type     MOID     a     e     i     H  Mag  Discoverer      MPEC
2010 SE12   Amor    0.115   1.36  0.18   9.3  24.3  20  Spacewatch      2010-S34
2010 SD12   Amor    0.076   1.80  0.41  23.6  23.8  20  Mount Lemmon    2010-S33
2010 SA12   Amor    0.147   2.25  0.50   6.2  20.8  20  Mount Lemmon    2010-S32
2010 SX11   Apollo  0.026   1.16  0.25   5.3  24.8  20  Spacewatch      2010-S30
2010 SZ3    Apollo  0.014   1.18  0.14   2.0  28.3  20  Mount Lemmon    2010-S26
2010 SY3    Amor    0.224   2.08  0.41   6.0  22.8  21  Mount Lemmon    2010-S25
2010 SX3    Amor    0.066   1.59  0.33   8.0  24.9  20  Mount Lemmon    2010-S24
2010 SW3    Apollo  0.0005  1.62  0.40   1.6  26.6  20  Mount Lemmon    2010-S23
2010 SV3    Apollo  0.056   1.51  0.52   6.2  20.5  19  Catalina        2010-S21
2010 ST3    Apollo  0.040   2.06  0.53   3.8  25.1  21  PanSTARRS       2010-S20
2010 SS3    Amor    0.393   1.61  0.24  26.9  20.8  21  Mount Lemmon    2010-S19
2010 SR3    Amor    0.187   1.74  0.37  12.2  21.8  21  Mount Lemmon    2010-S18
2010 SP3    Apollo  0.004   1.98  0.63   0.4  24.6  18  Catalina        2010-S16
2010 RG137  Amor    0.105   2.36  0.55   9.9  21.0  19  Mount Lemmon    2010-S15

Comet       Type       T        q     a     e     i  Mag  Period        MPEC 
C/2010 S1 (LINEAR)
            LPC    2013-05-09  4.41       1.0  126.9  17                2010-S41
2010 BK118 (discovered by WISE, rediscovered by LINEAR)
            ECC    2010-01-01  6.12 293.7 0.98 143.9  19  5030          2010-S26

Type
Aten -  Earth crossing with semi-major axis (avg distance from Sun) < 1 AU
Apollo - Earth crossing with semi-major axis (avg distance from Sun) > 1 AU
Amor - non-Earth crossing with perihelion distance < 1.3 AU
JFC - Jupiter family comet
HFC - Halley family comet
LPC - Long-period comet
MBC - Main belt comet
ECC - Suspected extinct or dormant (or just unrecognized) comet
T - Date of Perihelion
MOID - Minimum Orbit Intercept Distance, minimum distance between asteroid and Earth's orbit
a - semi-major axis, average distance from Sun in AU (1 AU = 93 million miles)
e - eccentricity
i - inclination
H - absolute magnitude
Mag - magnitude at discovery
Discoverer - survey or person who discovered the object
MPEC - Minor Planet Electronic Circular, the discovery announcement

Recent Discoveries – Sept 13, 2010

Two days ago 10 NEAs were announced, yesterday saw only a single announcement. The reason… most asteroid surveys are located in the southwest US (Arizona and New Mexico) so a bout of clouds over this part of the country will put a major dent in the number of discoveries. Hopefully the discoveries will ramp back up again tonight.

Yesterday’s sole announcement was larger than most recent discoveries. Nowadays most of the larger NEAs have been found. 2010 RO82 is probably somewhere between 3/4 of a km and 2.5 km across. Chances are an object this big and bright has been seen before though it may not have been recognized as an NEA. Though it is an NEA it really doesn’t come very close to Earth (MOID of 0.163 AU).

Asteroid    Type     MOID     a     e     i     H  Mag  Discoverer      MPEC
2010 RO82   Amor    0.163   2.47  0.60  18.0  16.9  19  Siding Spring   2010-R107

Comet       Type     MOID     q     a     e     i  Mag  Discoverer      MPEC
None

Type
Aten -  Earth crossing with semi-major axis (avg distance from Sun) < 1 AU
Apollo - Earth crossing with semi-major axis (avg distance from Sun) > 1 AU
Amor - non-Earth crossing with perihelion distance < 1.3 AU
JFC - Jupiter family comet
HFC - Halley family comet
LPC - Long-period comet
MBC - Main belt comet
MOID - Minimum Orbit Intercept Distance, minimum distance between asteroid and Earth's orbit
a - semi-major axis, average distance from Sun in AU (1 AU = 93 million miles)
e - eccentricity
i - inclination
H - absolute magnitude
Mag - magnitude at discovery
Discoverer - survey or person who discovered the object
MPEC - Minor Planet Electronic Circular, the discovery announcement

Hayabusa Returns to Earth

At 1400 hours UT on Sunday June 13 a brilliant fireball will appear over Australia. Unlike most fireballs this one won’t be due to a small asteroid but a returning man-made spacecraft. The Japanese Hayabusa (originally called MUSES-C for Mu Space Engineering Spacecraft C) is returning home after a harrowing 7 year mission to a small near-Earth asteroid and back. Harrowing in that almost anything that could go wrong did go wrong. Yet, if all goes well Hayabusa will be the first spacecraft to return samples from an asteroid.

[NOTE: A team from NASA will observe and study the resulting fireball from a NASA research DC-8 aircraft. The airborne team will attempt to broadcast video of the even live. Live video will be shown at 13:45-13:55 UT (9:45-9:55 am EDT).]

Sketch of Hayabusa spacecraft hovering over the surface of asteroid Itokawa during sample collection. Credit: Wikipedia public domain.

Launched in May of 2003, Hayabusa spent just over 2 years traveling to the half-km in diameter Earth-crossing asteroid (25143) Itokawa. In November of 2005 two sample attempts were made. The plan was for Hayabusa to hover a few meters above the asteroid’s surface, fire a small projectile into the surface, and collect any material that was thrown upwards. Due to spacecraft hardware and software control failures mission operators are unsure if any samples were collected. In fact, no one is completely sure what happened when Hayabusa reached the asteroid’s surface due to a loss of contact.

Due to the great work of the mission team, the hobbled spacecraft was coaxed back to Earth in spite of losing its reaction wheels, reaction control system (fine thrusters), and some of its ion thrusters (main propulsion). Regardless of whether Hayabusa successfully lands in Australia on Sunday or whether or not it contains any samples from Itokawa, the mission was highly successful and produced some great data on a small near-Earth asteroid.

Image of asteroid Itokawa by the Japanese Hayabusa spacecraft. Credut: JAXA.

2010 KQ – a very small, very close asteroid

Small asteroids buzz past the Earth every day. The great majority of them pass by sight unseen. One little asteroid, now named 2010 KQ, was picked up by the Catalina Sky Survey on the night of May 16. The fact that this object is small and passing close to Earth is not unusual. Rather it’s orbit is the interesting thing about  this object.  2010 KQ has an orbit that is very Earth-like as the diagram and table below shows.

Orbit of 2010 KQ and the inner planets. Created with C2A. Credit: Carl Hergenrother.

Orbital Parameters:
Perihelion distance = 1.016 AU
Aphelion distance = 1.032 AU
Semi-major axis = 1.024 AU
Inclination = 0.07°
Period = 1.04 years

Currently the official orbit sources give 2010 KQ an absolute magnitude (H) of 28.3 which corresponds to a diameter of 3-8 meters. This H value makes a few assumptions. My independent analysis of it brightness suggests it might be smaller and fainter with an H value of 29.9. This results in smaller diameters of 2-6 meters. Either way this is a small asteroid and only a handful of smaller ones have been detected. I will be able to better define these values as more observations are made.

The very Earth-like orbit creates very slow, long Earth fly-bys. Close approach happened yesterday (May 21) at a distance of 0.0033 AU (~490,000 km or 290,000 miles). That’s just a little further than the Moon.

Small objects on similar orbits have been found in the past. Only one of these objects turned out to be a natural asteroid. All of the others were man-made space hardware. Just like on Earth where it is hard to travel anywhere without running across man-made structures or garbage, space is also littered with working and non-working satellites, rocket bodies, and assorted nuts and bolts.

Bill Gray does an excellent job of monitoring these sorts of objects and determining whether they are natural or man-made. He studies the motion of the objects along their orbits. Man-made objects are light and have a large surface area to mass ratio. This allows the solar wind and other non-gravitational forces to change the motion of the objects. Within a week or so, he should have enough data to declare the object an asteroid or just space junk. He has set up a site where you can follow the current orbit of KQ and his current thoughts on its nature.

The last time KQ was in the vicinity of Earth was back in August 1990. Prior to that it passed Earth in 1975. Perhaps it is a piece of an interplanetary or high-Earth orbit spacecraft mission launched during those times (though the 1990 date already looks unlikely).

Asteroid Fly-By Today

A few hours from now (around 2 hours UT on April 9), a small ~20-meter in diameter asteroid will pass close to the Earth. At that time, asteroid 2010 GA6 will be about 10% closer to Earth than the Moon or 270,000 miles. Even though this is relatively close by asteroid standards, the small object will not be very bright (magnitude 15.5 to 16.0) and will be impossible to see without a camera-equipped telescope.

The asteroid was first picked up by the Tucson-based Catalina Sky Survey early on the evening of April 4. Events of this nature are detected a few times a year and may occur every few weeks. Still there is nothing to worry about. Space is big and these objects are small.

More info and a nice orbit diagram can be found at the JPL NEO Project Office.

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